[GHC] #3586: Initialisation of unboxed arrays is too slow

[GHC]

#3586: Initialisation of unboxed arrays is too slow
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    Reporter:  simonpj                   |        Owner:                  
        Type:  run-time performance bug  |       Status:  new             
    Priority:  high                      |    Milestone:  6.12.2          
   Component:  libraries (other)         |      Version:  6.10.4          
    Severity:  normal                    |   Resolution:                  
    Keywords:                            |   Difficulty:  Unknown         
    Testcase:                            |           Os:  Unknown/Multiple
Architecture:  Unknown/Multiple          |  
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Comment (by simonpj):

 Replying to [comment:13 int-e]:
 > On to more serious matters - the explicitely inlined worker trick works
 for ghc 6.10.4, but is not sufficient for the 6.12 RC, so that will need a
 different fix. One idea that works is to add
 > {{{
 > newArray = newArrayImpl
 > }}}
 > to all {{{MArray (STUArray ...) ...}}} instances. Of course getting
 inlining for default methods to work would be preferable. In fact, for
 default method it would be nice to have a special form of the SPECIALIZE
 pragma as well, one that duplicates the definition for all instances and
 optimizes it in that context.

 There's an underlying problem, which is the fragility of inlining of
 default methods. I'm in the midst of fixing that (the long-awaited INLINE
 patch), so I propose not to contort the libraries meanwhile.  I'll ping
 when I commit the patch so that you can check that it does improve
 matters.

 The only downside is that this perf boost won't get into 6.12, but I think
 it's too bad.

 Simon

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3586#comment:18>
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